Revellers erupted in cheers amid a confetti-filled celebration in New York's Times Square to welcome in the new year, part of star-studded celebrations and glittering fireworks displays around the world to usher in 2012.

Hurricane Irene has weakened to a tropical storm as it raced across New York City, leaving behind a stunned east coast where at least nine people died, severe flooding was widespread and four million homes were without power.